Utilities distribute power at high voltages, usually in excess of 1,000 volts, typically up to 35 kV. Line faults at these high energy levels can cause extensive damage to circuit components and devices connected to the circuit, or the conductors and various other portions of the electrical distribution system. To minimize potential damage, fuses are employed with the intent to interrupt current flow quickly following the onset of fault conditions involving high current loadings such as a short circuit or overload faults.
One such type of fuse is a back-up current limiting fuse which is applied in series with a low current protective device. The low current protective device typically is an expulsion fuse, such as a cutout fuse link, transformer internal weak link, etc. Thus, the expulsion fuse and current limiting fuse are designed to provide fault protection over a certain range of currents. The expulsion fuse is chosen to clear the low magnitude currents such as those produced by overloads and high impedance faults which are below the minimum current rating of the current limiting fuse. The back-up type current limiting fuse is selected to clear all other fault currents up to its maximum interrupting current. The current limiting fuse also provides the function of limiting the amount of energy that is let through to the source of the fault to a value below the withstand capability of the equipment being protected, thus reducing the risk of disruptive equipment failures.
Fuses can be connected into an electrical distribution system in a variety of ways. Typically, hardware in the form of complete connectors is attached to a terminal extending from the fuse endcap. The terminal itself takes various shapes such as a spade connector, a stud (either threaded or knurled) or a threaded aperture to receive, for example, an eyebolt connector. The connectors are generally added in their entirety by either bolting them on, screwing them in, or soldering to the fuse terminal. In some cases, manufacturers provide fuses with endcaps specially made to accept a particular type of connector. For example, the fuse could be made to have a spade connector on one end and a stud on the other. Thus, multiple types of connectors and/or endcaps with different fuse terminals were needed in order to provide different hardware options depending upon the application. This makes it difficult for utilities to order fuses and for utility workers who would need to bring several different fuses and hardware to a jobsite depending upon the arrangement of the distribution equipment. Furthermore, in the situation where connectors are attached to the fuse terminal by bolting or the like, extra electrical joints are created which could deteriorate over time and affect the operation of the fuse. Accordingly, it would be beneficial to design a fuse terminal which can accept the different hardware connectors and reduce the number of electrical joints in the circuit.